A turbocharger for use with an internal combustion engine may typically include a compressor that may be driven by a turbine or other rotation imparting device. The turbine may have a wheel connected to a compressor wheel by a common shaft that is supported for rotation by bearings. The bearings may be disposed in a housing that may be situated between the turbine and the compressor. To provide additional operational options, electric assisted turbochargers may include an electric motor that may be operated to supplement the rotational input provided by the turbine.
A turbocharger's rotor assembly may rotate at speeds that approach hundreds of thousands of revolutions per minute. In addition, the turbine may be exposed to high temperature exhaust gases and the resulting heat may be transferred to other system components. Under these harsh, and increasingly demanding operating conditions, the lifespan of a turbocharger is expected to match that of the engine with which it operates. To accomplish that challenge, the design of a turbocharger and its components must perform as expected, while still being cost effective and competitive.